This invention relates to an appliance for dispensing hot water, and more particularly, but not exclusively, to an appliance for brewing coffee.
A conventional drip coffee brewing appliance comprises a water reservoir for receiving cold water, and an electrically heated hot plate on which a carafe for receiving brewed coffee beverage is placed. A filter for receiving coffee grounds is placed in the open neck of the carafe. A tube extends from the bottom of the reservoir to a location over the filter. The tube passes under the hot plate, so that water in the tube is heated. The water is partially vaporized, and is forced upwards through the tube so that it is discharged into the filter. This type of appliance is subject to disadvantage in that the coffee beverage in the carafe continues to be heated so long as the hot plate is energized, and it is widely accepted that the flavor of a coffee beverage is degraded if the beverage is heated.
The microwave oven is used for a wide variety of heating tasks. It is well known to use a microwave oven to reheat coffee beverage.
Several devices for brewing coffee in a microwave oven have been proposed. For example, U.S. Pat. No. 4,104,957 issued Aug. 8, 1978 (Freedman et al) discloses a coffee brewing appliance comprising a carafe, a filter that fits in the neck of the carafe, and a reservoir located over the filter. The reservoir communicates with the filter by way of a thermally controlled valve. Therefore, when water in the reservoir is heated by microwave radiation, the valve opens and allows the water to flow into the filter for extracting coffee constituents from coffee grounds in the filter, so that a coffee beverage accumulates in the carafe.
U.S. Pat. No. 4,577,080 issued Mar. 18, 1986 (Grossman) discloses an appliance similar to that of Freedman et al, except that instead of using a thermally controlled valve to prevent cold water from the reservoir from contacting the coffee grounds in the filter, a body of non-toxic wax that melts when the water reaches the desired temperature is employed.
U.S. Pat. No. 4,721,835 issued Jan. 26, 1988 (Welker) discloses a device for brewing coffee in microwave oven. The device comprises a jug having a top configured as a filter. Water and coffee grounds are placed in the jug, and the filter is fitted in the mouth of the jug. When the coffee has brewed, it can be poured from the jug and the coffee grounds are retained by the filter.
U.S. Pat. No. 4,386,109 issued May 31, 1983 (Bowen et al) discloses an espresso coffee brewer for use in a microwave oven. The device disclosed by Bowen et al is generally similar to that of Freedman et al, except that instead of employing a thermally controlled valve to prevent flow of cold water through the coffee grounds, the coffee grounds are compressed so that they themselves form a seal. The reservoir is closed at the top, so that when the water in the reservoir is heated, the pressure rises sufficiently to force steam and water through the coffee grounds into the carafe.
U.S. Pat. No. 4,381,696 issued May 3, 1983 (Koral) discloses a coffee brewing appliance that is generally similar to that disclosed by Freedman et al.
U.S. Pat. No. 4,345,512 issued Aug. 24, 1982 (Moore) discloses a tea infuser for use in a microwave oven. The tea infuser, instead of being made of metal as is conventional, is made of a microwave transparent synthetic plastic material.
It has accordingly been well recognized that it would be convenient to be able to brew coffee or other beverages in a microwave oven. However, the known devices for accomplishing this are all subject to substantial disadvantages, such as the need for moving parts or foreign substances to control flow of water into contact with the coffee grounds.